<template>
  <!-- 商品分类导航 -->
  <div class="type-nav">
    <div class="container">
      <div @mouseenter="isEnterNav = true" @mouseleave="isEnterNav = false">
        <h2 class="all">全部商品分类</h2>
        <transition name="nav">
          <div
            v-show="navIsShow"
            @click="navToSearch"
            class="sort"
            @mouseleave="leaveCategory"
            @mouseenter="isInCategory = true"
          >
            <div class="all-sort-list2">
              <div
                @mouseenter="mouseEnterThrottleFn(index)"
                class="item"
                v-for="(category1, index) in categoryList"
                :key="category1.categoryId"
              >
                <h3
                  :style="{ background: isEnterIndex === index ? 'pink' : '' }"
                >
                  <a
                    :data-category1Id="category1.categoryId"
                    :data-categoryName="category1.categoryName"
                    href="javascript:;"
                    >{{ category1.categoryName }}</a
                  >
                </h3>
                <div
                  class="item-list clearfix"
                  :style="{
                    display: isEnterIndex === index ? 'block' : 'none',
                  }"
                >
                  <div class="subitem">
                    <dl
                      class="fore"
                      v-for="category2 in category1.categoryChild"
                      :key="category2.categoryId"
                    >
                      <dt>
                        <a
                          :data-category2Id="category2.categoryId"
                          :data-categoryName="category2.categoryName"
                          href="javascript:;"
                          >{{ category2.categoryName }}</a
                        >
                      </dt>
                      <dd>
                        <em
                          v-for="category3 in category2.categoryChild"
                          :key="category3.categoryId"
                        >
                          <a
                            :data-category3Id="category3.categoryId"
                            :data-categoryName="category3.categoryName"
                            href="javascript:;"
                            >{{ category3.categoryName }}</a
                          >
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">尚品汇超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
  import { throttle } from "lodash";
  import { mapState } from "vuex";
  export default {
    name: "TypeNav",
    data() {
      return {
        //保存鼠标移入的item
        isEnterIndex: -1,
        // 保存鼠标在不在分类区域
        isInCategory: false,
        // 保存鼠标在不在整个nav区域
        isEnterNav: false,
      };
    },
    mounted() {
      // 使用lodash的节流方法
      this.mouseEnterThrottleFn = throttle(this.mouseEnterItem, 500, {
        leading: true, //指定调用在节流开始前
        trailing: true, //指定调用在节流结束后。
      });
    },
    computed: {
      ...mapState("category", ["categoryList"]),

      // nav的展示
      navIsShow() {
        // 主页会一直展示
        if (this.$route.name === "Home") return true;

        return this.isEnterNav;
      },
    },
    methods: {
      // 节流的真正的事件函数
      mouseEnterItem(index) {
        console.log(index);

        if (!this.isInCategory) return;

        this.isEnterIndex = index;
      },
      // 占位函数
      mouseEnterThrottleFn() {},

      // 离开分类
      leaveCategory() {
        this.isEnterIndex = -1;
        this.isInCategory = false;
      },
      // 跳转到search页面
      navToSearch(e) {
        if (e.target.nodeName !== "A") return;
        const { category1id, category2id, category3id, categoryname } =
          e.target.dataset;

        const params = this.$route.params;

        this.$router.push({
          name: "Search",
          query: {
            category1Id: category1id,
            category2Id: category2id,
            category3Id: category3id,
            categoryName: categoryname,
          },
          params,
        });
      },
    },
    watch: {
      $route() {
        this.isEnterNav = false;
      },
    },
  };
</script>

<style lang="less" scoped>
  .nav-enter,
  .nav-leave-to {
    opacity: 0;
  }
  .nav-enter-active,
  .nav-leave-active {
    transition: all 0.3s linear;
  }

  .type-nav {
    border-bottom: 2px solid #e1251b;

    .container {
      width: 1200px;
      margin: 0 auto;
      display: flex;
      position: relative;

      .all {
        width: 210px;
        height: 45px;
        background-color: #e1251b;
        line-height: 45px;
        text-align: center;
        color: #fff;
        font-size: 14px;
        font-weight: bold;
      }

      .nav {
        a {
          height: 45px;
          margin: 0 22px;
          line-height: 45px;
          font-size: 16px;
          color: #333;
        }
      }

      .sort {
        position: absolute;
        left: 0;
        top: 45px;
        width: 210px;
        height: 461px;
        position: absolute;
        background: #fafafa;
        z-index: 999;

        .all-sort-list2 {
          .item {
            h3 {
              line-height: 30px;
              font-size: 14px;
              font-weight: 400;
              overflow: hidden;
              padding: 0 20px;
              margin: 0;

              a {
                color: #333;
              }
            }

            .item-list {
              display: none;
              position: absolute;
              width: 734px;
              min-height: 460px;
              background: #f7f7f7;
              left: 210px;
              border: 1px solid #ddd;
              top: 0;
              z-index: 9999 !important;

              .subitem {
                float: left;
                width: 650px;
                padding: 0 4px 0 8px;

                dl {
                  border-top: 1px solid #eee;
                  padding: 6px 0;
                  overflow: hidden;
                  zoom: 1;

                  &.fore {
                    border-top: 0;
                  }

                  dt {
                    float: left;
                    width: 54px;
                    line-height: 22px;
                    text-align: right;
                    padding: 3px 6px 0 0;
                    font-weight: 700;
                  }

                  dd {
                    float: left;
                    width: 415px;
                    padding: 3px 0 0;
                    overflow: hidden;

                    em {
                      float: left;
                      height: 14px;
                      line-height: 14px;
                      padding: 0 8px;
                      margin-top: 5px;
                      border-left: 1px solid #ccc;
                    }
                  }
                }
              }
            }

            &:hover {
              .item-list {
                display: block;
              }
            }
          }
        }
      }
    }
  }
</style>
